DESCRIPTION

The ecvt() function shall convert value to a null-terminated string of ndigit digits (where ndigit
is reduced to an unspecified limit determined by the precision of a double) and return a pointer to the string. The
high-order digit shall be non-zero, unless the value is 0. The low-order digit shall be rounded in an implementation-defined
manner. The position of the radix character relative to the beginning of the string shall be stored in the integer pointed to by
decpt (negative means to the left of the returned digits). If value is zero, it is unspecified whether the integer
pointed to by decpt would be 0 or 1. The radix character shall not be included in the returned string. If the sign of the
result is negative, the integer pointed to by sign shall be non-zero; otherwise, it shall be 0.

If the converted value is out of range or is not representable, the contents of the returned string are unspecified.

The fcvt() function shall be equivalent to ecvt(), except that ndigit specifies the number of digits
desired after the radix character. The total number of digits in the result string is restricted to an unspecified limit as
determined by the precision of a double.

The gcvt() function shall convert value to a null-terminated string (similar to that of the %g conversion
specification format of printf()) in the array pointed to by buf and shall
return buf. It shall produce ndigit significant digits (limited to an unspecified value determined by the precision
of a double) in the %f conversion specification format of printf() if
possible, or the %e conversion specification format of printf() (scientific
notation) otherwise. A minus sign shall be included in the returned string if value is less than 0. A radix character shall
be included in the returned string if value is not a whole number. Trailing zeros shall be suppressed where value is
not a whole number. The radix character is determined by the current locale. If setlocale() has not been called successfully, the default locale, POSIX, is used. The
default locale specifies a period ( '.' ) as the radix character. The LC_NUMERIC category determines the value of
the radix character within the current locale.

These functions need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe.

RETURN VALUE

The ecvt() and fcvt() functions shall return a pointer to a null-terminated string of digits.

The gcvt() function shall return buf.

The return values from ecvt() and fcvt() may point to static data which may be overwritten by subsequent calls to
these functions.